Aircraft speed
Is this a trick question?
If you read the FAR's, it specifically states that only the FAA "Administrator" can authorize >250kts below 10K .... not to be confused with "ATC" which the FAR's clearly differentiate as in the very next paragraph of the FAR's.
§ 91.117 Aircraft speed.
(a) Unless otherwise authorized by the Administrator, no person may operate an aircraft below 10,000 feet MSL at an indicated airspeed of more than 250 knots (288 m.p.h.).
(b) Unless otherwise authorized or required by ATC, no person may operate an aircraft at or below 2,500 feet above the surface within 4 nautical miles of the primary airport of a Class C or Class D airspace area at an indicated airspeed of more than 200 knots (230 mph.). This paragraph (b) does not apply to any operations within a Class B airspace area. Such operations shall comply with paragraph (a) of this section.